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Re: [Xen-devel] [PATCH] Fix acpi_dmar_zap/reinstate() (fixes S3 regression)

On 22/01/13 13:58, Jan Beulich wrote:

Jan, thanks for your comments

I recognize the need of fixing this, but not this way. We have
ioremap() now, and hence the patch could be using this,
without re-running the whole acpi_get_table(), but just using
the stored physical address of the table (retrieving of which
would be the only real code addition needed here).

For the older trees with non-functional ioremap(), I'd prefer
simply adding the table range to the 1:1 mapping (thus making
ioremap() work for that range, should use of that be needed;
if not needed, that's certainly worth considering this even for

Also, with your change not even attempting to fix the underlying
issue of the ACPI code storing a pointer to the mapped table in
acpi_gbl_root_table_list.tables[].pointer, I can't even see how
your patch is supposed to work. I'd expect the stored pointer to
get re-used by acpi_get_table()/acpi_tb_verify_table(), and hence
this shouldn't win you anything.
It works because the existing code in acpi_get_table actually sets acpi_gbl_root_table_list.tables[i].pointer = NULL every call anyway (after setting *out_table pointer).

I'll have a go at trying this with ioremap() and retrievable table's physical pointer instead.

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